A printing bureau quote is built from a small number of measurable things: how much material the part consumes, how much of the machine's build volume it occupies, how long the machine is busy, which process you chose, and what finishing you asked for. Once you can see those five levers, the difference between two quotes for the same file stops being mysterious.
The five things a quote is made of
Material volume, including supports, which on some processes is most of what you pay for. Bounding box, because a tall thin part occupies build height that nobody else can use. Machine time, driven mainly by height in layer based processes. Process, since a resin part and a sintered nylon part are different machine economies. And finishing, which is where identical geometries diverge most.
How to make the same part cheaper
Orient it to reduce height and support material, and say so on the order rather than leaving it to the software. Hollow solid volumes where the part does not need to be solid, and add drain holes. Batch several parts into one order so they share a build. Choose the finish that answers the question rather than the one that looks best in the photograph.
What each process costs you in practice
Filament printing is the cheapest way to hold a shape and the worst finish. Resin printing gives fine detail and smooth surfaces and costs more per unit volume. Sintered nylon needs no supports and gives genuinely usable mechanical parts, priced by how densely the build can be packed. Metal is a different order of magnitude and carries post processing with it.
Lead time is a price, not a fact
Most bureaus sell the same part at several lead times, and the fastest is often several times the price of the standard one. That premium is scheduling rather than cost, so it is worth asking what the part costs on a five day clock before defaulting to next day. If the review is a fortnight away, the fast slot buys nothing at all.
Questions people ask about 3d printing services
How much does 3D printing cost?
For a small filament part, very little. For a resin or sintered nylon part, more, and for a metal part, an order of magnitude more again. The honest answer needs the process, the volume, the bounding box and the finish.
Why is my tall thin part so expensive?
Layer based machines charge for height. A part that is tall in the build occupies the machine for a long time even if it uses very little material, so reorienting it often halves the price.
Do supports cost money?
Yes, twice: the material they consume and the labour to remove them and finish the surface underneath. Orienting to reduce supports is the single most effective saving on most parts.
Is it cheaper to order ten at once?
Usually, because they share a build and a setup. Ask for a price at one and at ten with the same quote and the shape of the saving becomes visible.